1. Field of the Invention
The present invention relates to a process for preparing poly(silvinylene)s and to poly(silvinylene)s having a novel structure that has vinyl groups each regularly introduced between the silicon atoms of adjacent Si-Si bonds.
2. Description of the Prior Art
The 1,2-addition reaction of a disilane to an acetylene bond is studied in detail using as a catalyst various transition metal complexes.
According to the above study, for example, in a disilane wherein a silicon atom is activated, for example, by an electron attractive group bonded to the silicon atom, when it is reacted with an acetylene compound, the 1,2-addition reaction proceeds preferentially to form an addition reaction product, but the yield is generally low.
For example, in the reaction between sym-tetramethyldisilane [HMe.sub.2 SiSiMe.sub.2 H] and dimethylacetylene dicarboxylate [MeOOC--C.tbd.CCOOMe], the yield of dimethyl-.alpha.,.alpha.'-bis(dimethylsilyl) maleate, that is, the 1,2-adduct (formation of a cis-form), is 40%. In a similar reaction by phenylacetylene, a ring formation reaction proceeds preferentially over the addition reaction and while the yield of 1,1-dimethyl-3,4-diphenyl-1-silacyclopentadiene is 45%, the yield of cis-1,2-bis(dimethylsilyl)-1-phenylethylene, that is, the 1,2-adduct, is only 25%.
Further, it is pointed out that, in the reaction using a phosphine complex catalyst of nickel or platinum, the ring formation reaction is more preferential, and the principal product is a compound having a silacyclo ring [H. Okinoshima et al., J. Organomet. Chem. 86 C27-C30 (1975)].
Japanese Pre-examination Patent Publication (KOKAI) Nos. 88224/1979 and 88225/1979 disclose the preparation of cis-1,2-adduts by reacting a methyldichlorosilane with an acetylene in the presence of a palladium complex catalyst. However, in the case using a hexamethyldisilane, the yield is low as shown in the Comparative Examples.
That is, a process has not yet been found wherein a disilane whose substituents all are alkyl groups such as hexamethyldisilane is used to produce the 1,2-adduct for an acetylene type compound in high yield and a process capable of producing such a 1,2-adduct in generally high yield is desired.
A reaction for introducing regularly vinyl groups each between the silicon atoms of adjacent Si-Si bonds has not yet been known and such a compound has not been known.